1. Field of the Invention
The present invention relates to liquid dispensing containers that require venting, including drinking and feeding containers, for example, infant feeding bottles and cups. More particularly, the present invention relates to vent systems, including vent valves, vents and the like that are located at the bottom of such containers, to alleviate vacuum created in the containers during feeding. The present invention also relates to such vent systems that also prevent liquid from leaking from the containers.
2. Description of Related Art
Baby liquid feeding bottles have vent systems or means designed to allow air to flow into the bottle to alleviate the vacuum created in the bottle during feeding. Such baby bottles typically employ a nipple and are vented at the flange of the nipple. This is effective for alleviating the vacuum and dispensing the liquid but it allows air to enter the liquid and then be swallowed by the baby. The swallowed air can cause gas and colic. To keep air out of the liquid during feeding and to prevent the air from being swallowed by the feeding baby, some baby feeding bottles have been designed with vents removed from the nipples and placed at or near the bottom of the bottles. Such a venting system employs an elastomeric or silicone diaphragm with a plurality of slits therethrough. The slits are normally closed. They open to allow air to vent into the bottle when the baby sucks on the nipple to apply a negative pressure inside of the bottle. The slits close when the baby stops sucking on the nipple and the negative pressure is no longer applied. Such a venting system has proven effective for alleviating the vacuum, while also preventing leakage.
However, the aforementioned and other bottom venting systems that employ slits in flexible members such as diaphragms can be further improved in that the baby who is feeding needs to apply sufficient sucking pressure to the nipple to open the slit vents for venting vacuum and to actuate flow of the contained liquid, for example milk or formula. Since baby bottles employing bottom venting systems may contain about five to about six inches of liquid, the need of the infant to apply a sucking pressure to activate a slit venting system could be perceived as a problem in connection with placing a strain on infants having sensitive, developing or infected ears. Another area for improvement is associated with slit flexible members and the silicone materials by which they are made. When such materials are slit, the materials begin to heal at the slit, over time. The bonds in the slit silicone begin to reform such that the slits will not open as easily as when initially formed. When this occurs, the activation suction pressure to open the slits increases to a level higher than was initially required to activate the slit vent. Occasionally, the slits heal enough that they cannot open at all, and the infant cannot feed from the bottle. A further area for possible improvement is with respect to the use of silicone material itself as the flexible venting or valve member. While silicone generally is a suitable material, for example in that slits formed in silicone flexible members do not begin to open due to dishwashing and boiling heat, the material is very expensive. It would be desirable to develop a venting system that does not require that the flexible venting or valve member be made of a silicone material.